A variety of elevating apparatuses of this type are known. An example may be found in EP-A-0 403 410. Such devices are employed in workshops and factories where they are more or less bound to the area of the respective workshop or factory. Often it would, however, be desirable to have such device available at a distant workplace, e.g. to have it available for services or repairs at a client or at a construction site. The disadvantage of most of the elevating devices of the prior art, as also of the construction of EP-A-0 403 410, is that the rack necessarily forms an angle with the mast construction, and is in most cases perpendicular, thus rendering the elevating device quite bulky and hardly suited for transportation, especially in a vehicle of limited space, such as a van or a small delivery truck as is frequently used by the service personal.
It is true that it is known from EP-A-0 443 843 to construct an elevating apparatus, and particularly a mast, with all features mentioned in the introduction from individual parts to be plugged into one another. The rack has some relatively short protruding upright plug sockets on its upper surface into which the individual parts of a mast telescopically displaceable in height may be plugged in. The mast has an elevating platform secured to its uppermost portion, This design, however, has numerous disadvantages:
The plug sockets have to exhibit a certain minimum height. This adds in a certain way to the bulkiness of the construction.
Of course, the plug sockets may be made as short as possible to avoid to long protruding parts; but if they are made short, then a secure guidance and mounting of the other parts of the mast to be plugged in is not ensured. On the one hand the individual parts must have a certain tolerance or clearance in order to be able to plug the parts into one another. On the other hand, the plugged mast parts should fit into the plug sockets as close as possible in order to avoid unsure and unsteady mounting of the same. It is true that there are additional mounting brackets provided in the construction of the EP-A- to improve the stability of the mast, but they extend almost parallely to the mast so as to be unable to improve stability.
The individual parts of the mast have to be taken separately during travelling which is not only unconvenient, but results also in several loseable pieces.
Finally it not just an advantage if the elevating platform ist rigidly mounted at the top of the mast, because the top part of the mast can only be lowered to the extent that its bottom end props against the rack. Therefore, even in the lowermost position of the mast, the elevating platform will be relatively relatively high so that a ladder will be necessary (in addition) to be able to climb onto the platform.
An apparatus according to the above introduction is also known from CH-A-504379 or DE-C-2227470. In both cases, the rack is provided with supports raising from the beams or spars of the frame about in its center and bearing the tilting axis. This design is relative expensive and bulky. In case of a transport, the parts have to be dismounted so that handling is difficult and time consuming. Moreover, the dismounted parts have to be taken along as separate, and possibly loseable parts.